In a case where batteries such as a lithium battery in which an electrode laminated body and a liquid electrolyte are sealed inside an outer case body of the battery are manufactured, to improve permeability of the liquid electrolyte, there has been known a method in which the inside of a liquid injecting chamber is depressurized to a predetermined vacuum state by a liquid injecting vacuum pump, and in which, in the inside of this liquid injecting chamber which has been depressurized, the liquid electrolyte is injected through an opening portion of the outer case body of the battery (see Japanese Patent Application Publication H9-35704).
In this way, after injecting the liquid electrolyte in the vacuum state, for example, this battery is allowed to stand still in atmospheric pressure conditions for a certain period of time to progress impregnation of the liquid electrolyte. After that, the battery is transferred to a sealing chamber. By depressurizing the inside of this sealing chamber to the predetermined vacuum state, after exhausting a gas remaining inside the outer case body, the opening portion is sealed by heat-welding, etc.